Next page Module: Chemistry 1 Carbon Chemistry

The units in this module are: Next page The units in this module are: C1a – Cooking C1b – Food Additives C1c – Smells C1d – Making crude oil useful C1e – Making Polymers C1f – Designer Polymers C1g – Using Carbon Fuels C1h - Energy Click on the links to take to the topic you wish to revise.

C1a - Cooking Why we cook foods Methods of cooking Cooking proteins Next page C1a - Cooking Why we cook foods Methods of cooking Cooking proteins Raising agents Download podcast here Main menu

Next page Why do we cook foods? We cook foods for a number of reasons. Some of them are: To kill harmful microbes that may cause food poisoning To make the food easier to digest To improve the flavour of the food To improve the texture of the food Back to C1a Main menu

How can we cook foods? There are several ways to cook foods. Next page How can we cook foods? There are several ways to cook foods. Baking and roasting In an oven. Hot air surrounds the food Cakes, meat Boiling In boiling water. Vegetables can lose vitamins Eggs, potatoes Steaming In steam above water. Maintains vitamins. Vegetables, fish Frying In hot oil Chips, eggs Grilling Under a grill. Food is heated by direct radiation Steak Microwaving Uses waves to cook the food Fish, ready meals Back to C1a Main menu

Next page Cooking Proteins Eggs are a good source of proteins. We know it is a chemical change because the appearance changes. When you heat up proteins, the molecule changes shape. We say is has been denatured. Back to C1a Main menu

Next page Raising Agents When we make a cake it is important it rises. We add a raising agent. Baking powder is a raising agent which contains sodium hydrogen carbonate. When it is heated it decomposes (breaks down) Sodium Hydrogen  Sodium + Water + Carbon Carbonate Carbonate Dioxide 2 NaHCO3  Na2CO3 + H2O + CO2 Back to C1a Main menu

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C1b - Food Additives Types of food additives E-numbers Next page C1b - Food Additives Types of food additives E-numbers Emulsifiers and Antioxidants Active packaging Download podcast here Main menu

Types of Additives Food colours Antioxidants Emulsifiers Flavour Next page Types of Additives Food additives are chemicals added to food to improve or enhance it. Food colours Make the food look more attractive Antioxidants Slows down food going off by slowing down the reaction with oxygen Emulsifiers Keeps ingredients thoroughly mixed Flavour Improve the flavour of the food Back to C1b Main menu

E-Numbers E100 – 199 Food colours E200 – 299 Preservatives E300 – 399 Next page E-Numbers Some additives have been approved for use in the EU. These additives have E-numbers. The E-number tells us what the additive is used for. E100 – 199 Food colours E200 – 299 Preservatives E300 – 399 Antioxidants E400 – 499 Emulsifiers E600 - 699 Flavourings Back to C1b Main menu

Emulsifiers Oil and water do not mix Next page Emulsifiers Oil and water do not mix Emulsifiers keep them mixed together in mayonnaise. An emulsifier molecule has two parts. The hydrophilic head bonds to water molecules. The hydrophobic tail bonds to the oil molecules. This prevents oils molecules from joining together. Back to C1b Main menu

Next page Active Packaging Active packaging can be used to improve the safety or quality of food. Examples Wrapping in plastic film keeps out oxygen and water which keeps the food crisp Some packaging removes water to stop food inside going off Antioxidants are added to some foods or packaging to stop them reacting with oxygen. Back to C1b Main menu

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C1c - Smells Esters Making esters Properties of perfumes Solvents Next page C1c - Smells Esters Making esters Properties of perfumes Solvents Download podcast here Main menu

Esters Esters are a group of chemicals that provide scents. Next page Esters Esters are a group of chemicals that provide scents. They can occur naturally or can be made synthetically Esters can be used in foods like sweets They can also be used in perfumes Back to C1c Main menu

Next page Making Esters Esters can be made by reacting an organic acid with an alcohol. It produces an ester and water. A drop of concentrated sulphuric acid acts as a catalyst. Organic acid + Alcohol  Ester + Water Methanoic acid + Ethanol  Ethyl Methanoate + Water Marzipan Benzoic acid Methanol Methyl benzoate Wintergreen Salicylic acid Methyl salicylate Pear drops Ethanoic acid Ethanol Ethyl ethanoate Pineapple Butanoic acid Methyl butanoate Scent Acid Alcohol Ester Back to C1c Main menu

Properties of Perfumes Next page Properties of Perfumes Perfumes need certain properties if they are to be used. Evaporate easily Perfume particles reach noses and people can smell it Non-toxic Doesn’t poison us Not react with water Doesn’t react with sweat Insoluble Doesn’t wash of easily Non-irritant Able to be put on the skin We can smell perfumes because they evaporate when put on the skin. This is because the skin is warm. Back to C1c Main menu

Solvents Esters can be used as solvents Next page Solvents Soluble If a substance can be dissolved in a liquid Insoluble If a substance cannot be dissolved in a liquid Solute The substance that is dissolved Solvent The liquid which does the dissolving Esters can be used as solvents Ethyl ethanoate can be used as nail varnish remover Nail varnish in insoluble in water so water cannot be used to take off varnish. A nail varnish remover must be used. Back to C1c Main menu

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C1d - Making Crude Oil Useful Next page C1d - Making Crude Oil Useful Separating crude oil Properties of fractions Cracking Problems with crude oil Download podcast here Main menu

Next page Separating Crude Oil Crude oil is a mixture of hydrocarbons. Hydrocarbons contain hydrogen atoms and carbon atoms. The crude oil can be split into more useful products by fractional distillation. Vapour enters at the bottom of the tower. As it passes up the tower, it cools. Fractions with high boiling points condense and are collected at the bottom. Fractions with low boiling points condense and are collected at the top. Back to C1d Main menu Main menu

Properties of Fractions Next page Properties of Fractions Bigger molecules have higher boiling points Bigger molecules are more viscous Bigger molecules are less flammable Hydrocarbon molecules in fractions are held together by forces of attraction called intermolecular forces. The stronger these forces are, the higher the boiling point. Bigger molecules have stronger intermolecular forces. Back to C1d Main menu

Next page Cracking The fractions that are used as fuels are in much higher demand. Oil companies can break large molecules into more useful, smaller molecules. This is called cracking. Cracking is a thermal decomposition reaction and requires heat and a catalyst. Cracking also converts large alkane molecules into smaller alkane molecules and an alkene molecule. Back to C1d Main menu

Problems with Crude Oil Next page Problems with Crude Oil Crude oil is a very useful chemical. However, there are lots of problems with it. Environmental problems Oil spills can pollute the seas, harm wildlife when they are coated with oil and beaches can be damages. Political problems Countries can argue and begin wars over who owns the oil. Back to C1d Main menu

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C1e - Making Polymers Alkanes Alkenes Polymerisation Next page C1e - Making Polymers Alkanes Alkenes Polymerisation Polymerisation diagrams Download podcast here Main menu

Next page Alkanes Alkanes are a group of hydrocarbons that contain only single covalent bonds. Known as saturated hydrocarbons. Alkanes have the general formula, CnH2n+2 Each carbon must have 4 bonds Each hydrogen must have 1 bond Back to C1e Main menu

Next page Alkenes Alkenes are a group of hydrocarbons that contain one or more double covalent bonds. Known as unsaturated hydrocarbons. Alkenes have the general formula, CnH2n We can distinguish between alkanes and alkenes using bromine water. Back to C1e Main menu

Next page Polymerisation Polymers are long chained molecules. The basic unit in a polymer is called a monomer. ethene + ethene + ethene  Poly (ethene) single units  many units Monomer Polymer Styrene Poly(styrene) Propene Poly(propene) Chloroethene Poly(chloroethene) Back to C1e Main menu

Polymerisation Diagrams Next page Polymerisation Diagrams We can show polymerisation by diagrams. The double bond in the monomer splits open. The double bond has become single bond The same groups are attached to the carbon atoms. Back to C1e Main menu

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C1f - Designer Polymers Uses of polymers Gore-Tex Next page C1f - Designer Polymers Uses of polymers Gore-Tex Disposal of polymers 1 Disposal of polymers 2 Download podcast here Main menu

Uses of Polymers Polymers have lots of different uses. Polymer Uses Next page Uses of Polymers Polymers have lots of different uses. Polymer Uses Properties Polythene Plastic bags, containers Light, flexible, easily moulded Polystyrene Packaging, insulation Light, poor conductor of heat Nylon Clothing, climbing rope Lightweight, waterproof, tough Back to C1f Main menu

Next page Gore-Tex Nylon has been used in clothing because it is tough, lightweight and is waterproof. However, it does not let water vapour out so sweat cannot escape. Gore-Tex has a membrane layer attached to nylon. Gore-Tex has all the advantages of nylon but it is also breathable. This means it lets water vapour out. Back to C1f Main menu

Disposal of Polymers 1 Polymers are non-biodegradable. Next page Disposal of Polymers 1 Polymers are non-biodegradable. There are different methods of disposing of polymers. Landfill - Advantages Landfill – Disadvantages Polymers do not have to be sorted out. Modern landfills do not create pollution. Plastics break down to make methane which can generate electricity. Distance to landfill sites so transport costs. New sites are in the country and take up valuable land. If too much methane builds up, explosions can occur. Incineration - Advantages Incineration – Disadvantages Burning plastics produces lots of heat energy. Polythene produces more energy than burning coal or oil. Saves fossil fuels No carbon dioxide put into atmosphere. Burning at low temperatures can produce harmful dioxins Old incinerators produce harmful gases. Back to C1f Main menu

Recycling - Advantages Recycling – Disadvantages Next page Disposal of Polymers 2 Recycling - Advantages Recycling – Disadvantages Plastic is lightweight even when compressed. Cheaper to recycle plastics than make then from scratch. Recycled plastics can be used to make lots of useful materials Some plastics can be broken down to make raw materials for other products. Plastics must be collected and sorted. Many plastics contain materials that need to be removed. Cost of transporting to nearest recycling plant. Recycled materials are weaker Back to C1f Main menu

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C1g - Using Carbon Fuels Choosing a fuel Complete combustion Next page C1g - Using Carbon Fuels Choosing a fuel Complete combustion Incomplete combustion Download podcast here Main menu

Next page Choosing a Fuel When you are choosing a fuel there are several things you need to consider. Remember TEACUPS T  toxicity, how poisonous is the fuel E  energy value, how much energy does it give A  availability, how easy is it to get C  cost, how expensive is it U  usability, how easy is it to use P  pollution, does it produce harmful gases S  storage, how easy is it to store Back to C1g Main menu

Fuel + Oxygen  Carbon Dioxide + Water Next page Complete Combustion Burning of fuels requires oxygen. If there is plenty of oxygen we get complete combustion. Fuel + Oxygen  Carbon Dioxide + Water The limewater turns cloudy proving carbon dioxide is made. A colourless liquid collects which boils at 100ºC proving it is water. Back to C1g Main menu

Incomplete Combustion Next page Incomplete Combustion If there is not enough oxygen present during combustion, then incomplete combustion takes place. Fuel + Oxygen  Carbon Monoxide + Carbon + Water Incomplete combustion produce less heat, more soot and poisonous carbon monoxide. Back to C1g Main menu

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C1h - Energy Exothermic and Endothermic Reactions Bond calculations Next page C1h - Energy Exothermic and Endothermic Reactions Bond calculations Energy from fuels Energy per gram Download podcast here Main menu

Exothermic and Endothermic Reactions Next page Exothermic and Endothermic Reactions Chemical reactions involve a transfer of energy. Exothermic reactions give out heat energy. The temperature increases during an exothermic reaction. Burning is a type of exothermic reaction. Endothermic reactions take in heat energy. The temperature decreases during an exothermic reaction. Back to C1h Main menu

Overall change = bonds broken – bonds made Next page Bond Calculations Each bond requires a specific amount of energy to break it. When a bond is made, it releases a specific amount of energy. We can work out an overall energy change by: Overall change = bonds broken – bonds made 4 x C—H = 4 x 413 = 1652 2 x C = O = 2 x 805 = 1610 1 x O = O = 1 x 498 = 498 4 x O – H = 4 x 464 = 1856 Overall change = 2150 – 3466 = - 1316 Joules Back to C1h Main menu

Next page Energy from Fuels We can compare the energy given out by different fuels using a calorimeter. Energy = mass x specific heat x temp rise Sample results = 100g water heated by ethanol Start temp = 20ºC End temp = 32ºC Mass of lamp at start = 105.57g Mass of lamp at end = 103.47g Energy = 100 x 4.2 x 12 = 5040 Joules Back to C1h Main menu

Next page Energy per Gram A useful comparison of the energy value of fuels is the energy given out per gram. Energy per gram = energy (J) mass of fuel burned (g) Back to C1h Main menu

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